The soluble, functional, oligomeric form of link protein will be characterized by sedimentation equilibrium experiments and gel chromatography. The stoichiometry of binding of link protein to hyaluronate and proteoglycan monomer will be examined. Methods will be developed for the immunofluorescent localization of proteoglycan monomer, link protein and certain functionally important matrix proteins intracellularly and in the intercellular matrix of epiphyseal cartilage growth plate. The methods will be applied to normal and chondrodysplastic human epiphyseal cartilage growth plate. Studies will be carried out to elucidate the biochemical mechanism by which protoglycan aggregates are structurally modified during enchondral ossification, so that they lose their capacity to inhibit mineralization, and so that mineralization spreads from matrix vesicles throughout the intercellular matrix in the zone of the lowermost hypertrophic chondrocytes.